Chapter 6 ~ Cell Division Flashcards
What are the three stages of the cell cycle?
Interphase, mitosis and cytokinesis
Explain the three stages of interphase
G1, which consists of protein synthesis and organelles replicating
S phase this is the synthesis phase. The DNA is replicated in the nucleus.
G2, this is the second growth phase. The cells increase in size and the energy stores are increased and the duplicated DNA is checked for errors
Explain, G0
G0, is the phase when the cell leaves a cycle
Why does the cell leave the cycle during G0
Either because of differentiation or the DNA of the cell is damaged
What are checkpoints?
the cell checks DNA for any errors which minimises the chances of duplicating any mutated DNA into the replicated cell.
Where do the checkpoints occur?
G1 checkpoint, which is at the end of the G1 base before the S phase it checks for cell size, nutrients, growth factor and DNA damage
G2 checkpoint, which is at the end of the G2 phase, and before the start of the mitotic phase, it is checked for cell size, DNA replication, and DNA damage
Spindle assembly checkpoint it checks for chromosome attachment to the spindle
What are the two types of nuclear division?
Mitosis and meiosis
What is mitosis used for?
Growth and repair
reproduction (asexual) in plants, animals and fungi
What are the four stages of mitosis?
Prophase metaphase, anaphase telophase
Explain prophase during mitosis
chromosomes condense
nuclear envelope disintegrates
centrioles move to each pole and form spindle fibres.
Explain metaphase during mitosis
chromosomes are moved by spindle fibres to the metaphase plate and held in position
Explain anaphase during mitosis
centromere holding pairs of chromosomes divide, chromatids separate and pulled to opposite poles by spindle fibres.
Explains telophase in mitosis
chromatids have reached poles and are chromosomes, they assemble at each pole and nuclear envelope reforms. chromosomes uncoil and nucleolus is formed. cytokinesis begins
cytokinesis in mitosis
actual division of cell into 2 separate cells
What is meiosis?
Meiosis is a type of cell division to form gametes
production of haploid cells
genetic variation via independent assortment and crossing over
How many stages are there in meiosis?
There are two stages of meiosis, meiosis one and meiosis two
Explain meiosis 1
Hint: prophase 1, metaphase 1 , anaphase 1, telophase 1
during prophase 1, the chromosomes condense, and the nuclear envelope breaks apart. The nucleolus disappears and spindle formation begins. The homologous chromosomes pair up which formed bivalents and the crossing over occurs.
During metaphase one, the homologous pairs of chromosomes assemble along the metaphase plate, maternal and paternal chromosomes end up facing it either pole. This is results in independent assortment, which results in many different combination of the allele facing the poles.
During anaphase one, the homologous chromosomes are pulled to opposite poles and chromatids stay joined. sections of the DNA which become entangled break off and rejoin which are called the chiasmata. When exchange occurs at the chiasmata it forms recombinant chromatids with genes being exchanged, genetic variation arises.
During telophase one, the chromosomes assembled at each pole and the nuclear membrane reforms. Chromosomes uncoil and the cell undergo cytokinesis and divides into two cells.
Explain meiosis 2
During prophase 2, the chromosomes, condense nuclear envelope breaks down and spindle formation begins.
During metaphase 2, the individual chromosomes assemble on the metaphase plate, due to crossing over the chromatids are no longer identical so there is more independent assortment and more genetic variation
during anaphase 2, the chromatids of individual chromosomes are pulled to opposite poles after division of the centromeres.
During telophase 2, the chromatids assemble at poles. chromosomes uncoil and form chromatin. the nuclear envelope reforms. The nucleolus becomes visible, and cytokinesis results in the division of cell forming for daughter cells.
What are specialised cells?
Differentiated cells which are specialised to carry out a specific function
What are the five types of specialised cells
Hint: Emily not Sam play golf
1.Erythrocytes.
2.neutrophils
3.sperm cells
4.Palisade cells.
5. Guard cells
Explain the structure and function of erythrocytes
They have a biconcave shape which increases the surface area for diffusion and increases the cell flexibility for it to fit through narrow capillaries
Explain the structure and function of neutrophils
It has a lobbed nucleus and a granular cytoplasm. The cells are flexible which enables them to engulf pathogens. They contain lysosomes filled with hydrolytic enzymes lysozyme.
Explain the structure and function of sperm cells
The flagellum contains many mitochondria to release energy.
Acrosome in the head contains digestive enzyme to digest the wall of the egg ell so sperm can penetrate and fertilise egg cell
Explain the structure function of palisade cells
It is located in the Mesophyll tissue of leaves. It is a rectangular and tightly packed cells which contains many chloroplast to absorb and maximise light energy for photosynthesis. It contains thin walls to reduce the diffuse distance of carbon dioxide.
